Wireless communication systems have evolved into high-speed and high-quality wireless data packet communication systems for data and multimedia services, which is far beyond the voice-oriented services for which the wireless communications systems were initially developed. For example, Universal Mobile Telecommunications System (UMTS) systems, which are 3-Generation (3G) wireless communication systems based on Global System for Mobile Communication (GSM) and using Code Division Multiple Access (CDMA), provide a seamless service capable of transmitting packet-based text, digitalized voice or video, and multimedia data at a high speed of 2 Mega-bits per second (Mbps) or more to radiophone or computer users wherever they are located. These UMTS systems employ a concept of packet-switched access using a packet protocol such as an Internet Protocol (IP), and are always accessible to any other terminal within a network.
In a 3rd Generation Partnership Project (3GPP), which is for standardizing UMTS systems, Long Term Evolution (LTE) systems are being considered as next-generation wireless communication systems of the UMTS systems. These LTE systems are technologies for implementing high-speed packet-based communication of 100 Mbps or more. This can be accomplished several different ways. As an example, a way of simplifying a network structure and reducing the number of nodes located on a communication path, it may be possible to make wireless protocols closer to a maximum number of wireless channels.
FIG. 1 illustrates a role of a Media Access Control (MAC) layer for a wireless communication system according to the related art.
Specifically, FIG. 1 illustrates that Radio Link Control (RLC) Service Data Units (SDU) 101 and 103 are constructed and transmitted as one MAC SDU #1 120 to a MAC layer 130 through RLC #1 110, and an RLC SDU 105 is constructed and transmitted as one MAC SDU #2 122 to the MAC layer 130 through RLC #2 112.
Referring to FIG. 1, in the RLC #1 110 and RLC #2 112, the RLC SDUs 101, 103, and 105 received from an upper layer are constructed and transmitted as one RLC Protocol Data Unit (PDU) to the MAC layer 130. In view of the MAC layer 130, the RLC PDU can be interpreted as the MAC SDU #1 120 and MAC SDU #2 122. The MAC layer 130 combines and constructs the MAC SDU #1 120 and MAC SDU #2 122 as one MAC PDU and transmits the MAC PDU to a Physical (PHY) layer 140. The MAC PDU can include MAC SDUs 120 and 122 for data transmission in the RLC #1 110 and RLC #2 112, and MAC SDUs 120 and 122 for control that is exchangeable in the MAC layer 130 between a transmitter and a receiver. Also, the MAC SDUs 120 and 122 for control can be transmitted, together with the other MAC SDUs for data transmission, within one MAC PDU, or can be singularly included and transmitted within the MAC PDU. Accordingly, a MAC PDU header should be constructed to distinguish the MAC SDUs for data transmission and the MAC SDUs for control.
FIG. 2 illustrates a construction of a MAC PDU in a wireless communication system according to the related art.
Referring to FIG. 2, the MAC PDU includes a MAC header 210, and a payload 220 including one or more MAC SDUs. The MAC header 210 includes a ‘length’ field indicating a length of a payload indicated by header information, and a Logical Channel ID (LCID) for distinguishing the MAC SDUs transmitted from several logical channels. If the MAC PDU has an extra space despite including all of control MAC SDUs and data MAC SDUs delivered from RLC, the remnant portion is filled with meaningless bits. This portion is called MAC padding 230.
The MAC padding 230 is generated because, at allocation, it is actually impossible to allocate only as many resources as a necessarily required size. Particularly, in a case of an UpLink (UL), a base station allocates the UL to a terminal in accordance to a UL channel situation and a buffer state reported by the terminal. At this time, the total amount of the UL allocation is divided on a per-Time Transmission Interval (TTI) basis in accordance to the reported buffer state. The base station cannot accurately predict the buffer state because the buffer state itself is not precise and information of a time when transmitting the buffer state and the buffer state of an actual allocation time point. Also, because the UL allocation follows a Modulation and Coding Scheme (MCS) and a combination of Resource Blocks (RB), it is impossible to perform allocation of a precise size. Accordingly, the base station continuously performs allocation till a time point of generation of allocation in which the entire resources are all padding. The thus generated MAC padding is meaningless information, so there is a need for a way to more efficiently use this MAC padding.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.